UNIT 4: DNA, Chromosomes, and Cell Division DAYSHEET 46: Meiosis and Sexual Reproduction

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1 UNIT 4: DNA, Chromosomes, and Cell Division DAYSHEET 46: Meiosis and Sexual Reproduction Name Biology I Date: Catalyst/Bellringer: Use your reading strategies as you read the article below about cancer. Then answer the questions at the bottom. Purpose: To find out what causes cancer Activate Prior Knowledge: What do you already know about cancer? CANCER Cancer is a family of diseases that are caused by genetic mutations, or mistakes in DNA. Mutations can be caused by many things, including exposure to UV rays or contact with certain chemicals (like those found in cigarettes). Mutations can also occur by random chance when the DNA is replicating. Usually mistakes are caught by the cell, but if they re not the cell could become cancerous. The mutations that cause cancer all have one thing in common they make the cell and grow and divide uncontrollably. In cancer cells, mitosis happens at a very fast rate. If one cell grows and divides uncontrollably, it can form a mass of cells called a tumor. The tumor can suck nutrients and oxygen away from nearby cells in the body, causing healthy cells to die. NORMAL CELLS CANCER CELLS Many tumors are benign (not dangerous). The tumor can be removed and the person can continue to live a healthy life. But sometimes the cells in a tumor can begin to spread to other parts of the body. When cancer cells spread, the cancer is said to be malignant. If this happens, the person may need to get surgery, chemotherapy, or radiation treatment to try to kill the cancer cells. 1. What is a mutation? 2. What are some things that can cause mutations? 3. What type of mutation causes cancer? 4. What is a tumor? 5. What does it mean when a tumor is malignant?

2 Activity 1: Cornell Notes Biology Objective / Essential Question: Main Ideas / Questions: 1. produces two cells with the t number of as the parent cells. Let s apply this to our (body) cells: How many chromosomes are found in each one of your somatic cells? We Now Have a Problem All living things must be able to.. We reproduce. In two parents provide cells to make offspring. If we use two cells that have 46 chromosomes, how many chromosomes would the newly formed offspring have? The Answer Some of your cells do not n contain chromosomes. (sex cells) only contain the number of chromosomes found in your (body) cells. _ 1. Why do we need to use specialized cells for sexual reproduction? 2. _ Humans produce types of gametes. Males produce cells in.

3 Main Ideas / Questions: Females produce (egg) cells in.. 3. When they fuse during, the magic number is reached once again. _ When gametes are formed, their chromosome number has to be occurs during a special set of cell divisions called. produces with the chromosome number of the original cell. New Vocabulary A cell that only contains the total number of chromosomes is. Haploid cells (gametes) are represented by the letter A cell that contains that number of chromosomes is called. Diploid cells (body cells) are represented by! Practice Problems If a fruit fly has 8 chromosomes omes in a cell of its intestines, what is its diploid number? How many chromosomes are present in a fruit fly ovum?

4 Main Ideas / Questions: 1. If a snake has 24 chromosomes in its gametes, what is its diploid number? A naked mole rate has 50 chromosomes in the cells that line its mouth. What is the naked mole rat s haploid number? _ is a in chromosomes, so that the gametes become cells. This is a two division process: : : Homologous chromosomes are separated : : Chromatids in each chromosome are separated Both divisions contain phases similar to the phases in mitosis: Meiotic Division I Meiotic Division II 5. - occurs when portions of a on one homologous chromosome are exchanged with a chromatid portions of the other homologous chromosome. Crossing Over Causes Once the chromatids are genetically different (crossing over), when they separate as chromosomes into new haploid gametes, all the gametes will be! _ Using crossing-over in your response, explain why your parents will never be able to recreate you again.

5 Main Ideas / Questions: In the Venn Diagram below, compare and contrast Mitosis and Meiosis using the information from the video lecture: Meiosis Mitosis 6. _ Problems with Chromosome Numbers: Trisomy 21 is a genetic disorder caused by an Commonly referred to as 7. _ Changes in an organism s chromosome structure are called There are four types of chromosomal mutations:

6 Main Ideas / Questions: 8. Inversion: 9. _ Translocation: 10. _ Deletion: 11. _ Insertion: _ Carefully study the chromosomal mutations below. Identify each chromosomal mutation as either an inversion, translocation, deletion, or insertion event.

7 Activity 2: Vocabulary Mastery Directions: Pick 6 terms from the notes that you are (a) have the most difficulty with or (b) believe to be the most important terms. Write them down in the chart below and then write the class definition (from your Cornell Notes). When you are done, call your teacher over to check your definitions and get a signature. Vocabulary Term Class Definition Activity 3: Biology Vocabulary Master Sheet Directions: Fill in the first two columns of your vocabulary master sheet with your terms and definitions from Activity 2. Once you complete the last two columns, call your teacher over to check your sheet and to receive a signature. Activity 4: Summary Directions: Write a one-paragraph summary of your Meiosis & Sexual Reproduction Cornell Notes. You must include all six of your vocabulary terms from activities 2 and 3 to receive credit for your summary.

8 Activity 5: Time to Practice! SOMATIC CELLS vs. GAMETES Determine if the cells below are SOMATIC (BODY) CELLS or GAMETES. If the cell is a SOMATIC CELL, write an S in the blank. If the cell is a GAMETE, write a G in the blank. EXAMPLE: S_ Eye cell 1. Cheek cell 2. Heart cell 3. Sperm cell 4. Skin cell 5. Nerve cell 6. Muscle cell 7. Egg cell 8. Lung cell 9. Liver cell 10. Hair cell 11. Stomach cell 12. Kidney cell DIPLOID vs. HAPLOID Determine if the cells below are HAPLOID or DIPLOID. If the cell is HAPLOID, write an H in the blank. If the cell is DIPLOID, write a D in the blank. EXAMPLE: D_ Eye cell 1. Cheek cell 2. Heart cell 3. Sperm cell 4. Skin cell 5. Zygote 6. Muscle cell 7. Egg cell 8. Lung cell 9. Liver cell 10. Hair cell 11. Gametes 12. Kidney cell SENTENCE COMPLETION Circle the answer that best completes the sentences below. 1. Human skin cells are (HAPLOID / DIPLOID) Human skin cells contain (23 / 46) chromosomes Human skin cells are (SOMATIC / GAMETE) cells 2. Human egg and sperm cells are ( HAPLOID / DIPLOID) Human egg and sperm cells contain (23 / 46) chromosomes Human egg and sperm cells are (SOMATIC / GAMETE) cells 3. After the sperm fertilizes the egg, the resulting zygote has (23 / 46) chromosomes.

9 HW46: Meiosis and Sexual Reproduction Name: Biology I Date: Below are the chromosome numbers for some common organisms. Fill in the blanks on the chart and then answer the questions. ORGANISM SOMATIC CELL (2n) GAMETE (n) Human Garden Pea 14 Fruit Fly 4 Tomato 24 Dog 78 Chimpanzee 24 Leopard frog 26 Corn What is the diploid number of chromosome in corn? 2. What is the haploid number of chromosome in corn? 3. What is number of chromosome in tomato somatic cell? 4. What is the number of chromosome in a leopard frog gamete? 5. Which cells in the human contain only 23 chromosomes? 6. What is the number of chromosomes in a human zygote? Calculating Chromosome Number: 1. Each giraffe somatic cell contains 20 chromosomes. How many chromosomes does a giraffe sperm cell contain? (A) 0 (B) 10 (C) 20 (D) An elephant egg cell contains 15 chromosomes. How many chromosomes are found in the fertilized elephant zygote? (A) 0 (B) 7.5 (C) 15 (D) 30